Question

Variation of viscous force (F) on a small sphere falling through a medium with
the radius of the sphere, is represented as:

Answer 1

Answer & Explanation:

The force on a small sphere falling through a medium can be calculated using Stokes Law :

where Force (F) = 6πηrv

where;

π = pi or 22/7 or 3.14

η = viscosity of medium

r = radius of sphere

v = velocity of falling sphere

Hence, radius can be represented as r = F / 6πηv

Answer 2

Answer:

F= ηAV/(3V /4π)⅓

Explanation:

viscosity can be calculated  as the force per unit area on the other hand With an ideal fluid (called a Newtonian fluid), it is also directly proportional to what is called the shear rate. Shear rate can be defined as the speed that the liquid is moving divided by the distance that is moves.

hence viscous force (F) on a small sphere falling  through a medium with the radius of the sphere, can be  represented as:

F= ηAV/r

radius of sphere= r=(3V /4π)⅓

F= ηAV/(3V /4π)⅓